The combination lock according to the present invention is an improvement on the combination locking mechanism disclosed in U.S. Pat. No. 4,627,250. This combination lock assembly, although improved over the art which proceeded it, contained several disadvantages which became apparent to the designer after much experimentation. The above noted disadvantages were inherent in the design of the previous combination locking mechanism and required a substantial revision of the locking assembly so as to overcome the disadvantages.
The first disadvantage of the previous assembly relates to the uneven pressure required to depress the push buttons once a single push button has already been depressed. If an operator of ill intention has equipment capable of sensing the uneven pressure, the initial combination number of a set combination could be sensed by sequentially depressing all of the numbers on the push button pad while simultaneously holding down another one of the numeric push buttons. Hence, the initial combination setting could be derived from trial and error.
The second disadvantage of the previous locking mechanism relates to the method by which the combination is set. The combination of the previous locking mechanism is set by an operator manually rotating the combination interposers by use of a pin or other slender object. If an operator is not sufficiently mechanically skilled, resetting the combination could become quite cumbersome.
The third disadvantage associated with the previous locking assembly relates to the length of the stroke of the push buttons when actuating the combination assembly. Owing to the advantageous configuration of the separate parts of the present lock assembly, the present invention lock assembly results in a significantly reduced button stroke. Hence, operation of the mechanism is more convenient.
The present invention is the result of a substantial redesign of the previously proposed locking mechanism and eliminates the disadvantages associated therewith.